The lawsuit alleges that the US Fish and Wildlife Service allowed a North Carolina landowner to kill an adult female red wolf in June.
Photograph: Layne Kennedy/Corbis

The US government has failed to properly protect the red wolf, one of the world’s rarest wolves, by allowing a member of the species’ small wild population to be killed, conservationists have claimed.

The US Fish and Wildlife Service has been taken to court by a coalition of environmental groups that argues it has not properly protected the endangered red wolf, with estimates of just 50 to 75 of the animals left in the wild in North Carolina.

A lawsuit filed with the US district court for the eastern district of North Carolina states that the FWS permitted a landowner to kill an adult female red wolf in June that was known to have mothered a total of 16 pups through four litters.

This killing, along with a previous shooting of a red wolf last year, represents a “direct violation” of regulations around the capture of wolves on private property, the lawsuit claims.

The environment groups – the Red Wolf Coalition, Defenders of Wildlife and the Animal Welfare Institute – also allege that the FWS has failed to properly review the status of red wolves and has unduly suspended the reintroduction of the species from captivity into the wild.

The red wolf, which is smaller than a grey wolf, weighing around 40 to 50lb, once roamed an area stretching from Missouri to Texas and into North Carolina. The species, a top predator in the region, was largely wiped out over the past 100 years due to shooting and habitat loss.

The species was effectively extinct in the wild in 1980 when the FWS took the remaining red wolves into captivity for breeding. From an initial population of 14, there are now around 200 in captivity. Given this captive population, the FWS does not consider the species to be in imminent danger of becoming extinct if a wild wolf is shot.

“The red wolf is in grave danger of extinction, and if the US Fish and Wildlife Service doesn’t step up and significantly modify its management approach for red wolves, we may never see this species in the wild again,” said Jason Rylander, senior attorney for Defenders of Wildlife.

“This species can’t afford to wait another minute. The US Fish and Wildlife Service needs to take serious action and work with state and local governments to ensure the red wolf doesn’t slip away.”

The FWS would not comment directly on the lawsuit but said that it is reviewing its recovery efforts for the species and was committed to its survival. A recovery team has been established and will report on the viability of the species in summer 2016.

“There are a whole range of actions going on,” said Tom MacKenzie, spokesman for the FWS’s south-east division. “We have a recovery team in place, a unique and wide-ranging recovery team and we will get perspectives from across the board, including from people who have problems with wolves.

“The wild red wolf has nonessential population status, which means we have enough in captivity to continue the species. We put them into North Carolina to continue them in the wild because North Carolina didn’t have coyotes then. We are looking now at whether this is working out.”